package Cipher;

use strict;
use warnings;

sub encode {
    my $plaintext = shift;

    # normalize
    (my $cipher = $plaintext) =~ s/[^\p{Alnum}]//g;
    $cipher = lc $cipher;

    # translate
    $cipher =~ tr/abcdefghijklmnopqrstuvwxyz/zyxwvutsrqponmlkjihgfedcba/;

    # wordify
    $cipher =~ s/(\p{Alnum}{5})(?=\p{Alnum})/$1 /g;

    return $cipher;
}

sub decode {
    my $cipher = shift;

    (my $plaintext = $cipher) =~ s/[^\p{Alnum}]//g;
    $plaintext =~ tr/zyxwvutsrqponmlkjihgfedcba/abcdefghijklmnopqrstuvwxyz/;

    return $plaintext;
}

__PACKAGE__;